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Table 1 The difference in hand hygiene compliance in 3047 pairs of overtly and covertly observed hand hygiene opportunities stratified by department, occupation, observation time, and location

From: Identifying heterogeneity in the Hawthorne effect on hand hygiene observation: a cohort study of overtly and covertly observed results

Overt observation Number of matched pairs (%)
Covert observation
Matched odds ratio p valuea
Hand rubbing/washing No hand rubbing/washing
Department
 Medicine (N = 1212)    3.0 < 0.001
  Hand rubbing/washing 510 (42.1) 418 (34.5)   
  No hand rubbing/washing 139 (11.5) 145 (12.0)   
 Surgery (N = 1258)    3.6 < 0.001
  Hand rubbing/washing 475 (37.8) 482 (38.3)   
  No hand rubbing/washing 135 (10.7) 166 (13.2)   
 Paediatrics (N = 463)    2.7 < 0.001
  Hand rubbing/washing 292 (63.1) 112 (24.2)   
  No hand rubbing/washing 41 (8.9) 18 (3.9)   
 Gynaecology/obstetrics (N = 114)    2.9 0.001
  Hand rubbing/washing 60 (52.6) 35 (30.7)   
  No hand rubbing/washing 12 (10.5) 7 (6.1)   
Occupation
 Nurse (N = 2105)    5.3 < 0.001
  Hand rubbing/washing 994 (47.2) 778 (37.0)   
  No hand rubbing/washing 146 (6.9) 187 (8.9)   
 Physician (N = 619)    1.6 < 0.001
  Hand rubbing/washing 241 (38.9) 179 (28.9)   
  No hand rubbing/washing 114 (18.4) 85 (13.7)   
 Caregiver (N = 106)    1.4 0.302
  Hand rubbing/washing 26 (24.5) 27 (25.5)   
  No hand rubbing/washing 19 (17.9) 34 (32.1)   
 Others (N = 217)    1.3 0.184
  Hand rubbing/washing 76 (35.0) 63 (29.0)   
  No hand rubbing/washing 48 (22.1) 30 (13.8)   
Timeb
 Day shift (N = 2493)    3.1 < 0.001
  Hand rubbing/washing 1120 (44.9) 838 (33.6)   
  No hand rubbing/washing 273 (11.0) 262 (10.5)   
 Early night shift (N = 516)    3.7 < 0.001
  Hand rubbing/washing 208 (40.3) 190 (36.8)   
  No hand rubbing/washing 52 (10.1) 66 (12.8)   
 Late night shift (N = 38)    9.5 < 0.001
  Hand rubbing/washing 9 (23.7) 19 (50.0)   
  No hand rubbing/washing 2 (5.3) 8 (21.1)   
Location
 Ward (N = 2034)    3.7 < 0.001
  Hand rubbing/washing 815 (40.1) 774 (38.1)   
  No hand rubbing/washing 208 (10.2) 237 (11.7)   
 Intensive care unit (N = 880)    1.9 < 0.001
  Hand rubbing/washing 498 (56.6) 211 (24.0)   
  No hand rubbing/washing 111 (12.6) 60 (6.8)   
 Outpatient department (N = 133)    7.8 < 0.001
  Hand rubbing/washing 24 (18.0) 62 (46.6)   
  No hand rubbing/washing 8 (6.0) 39 (29.3)   
Number of indications per hand hygiene opportunity
 1 (N = 2301)    3.1 < 0.001
  Hand rubbing/washing 963 (41.9) 801 (34.8)   
  No hand rubbing/washing 260 (11.3) 277 (12.0)   
 2 (N = 42)    2.7 0.227
  Hand rubbing/washing 28 (66.7) 8 (19.0)   
  No hand rubbing/washing 3 (7.1) 3 (7.1)   
Hand hygiene indication
 Before touching a patient (N = 270)    3.1 < 0.001
  Hand rubbing/washing 96 (35.6) 99 (36.7)   
  No hand rubbing/washing 32 (11.9) 43 (15.9)   
 Before clean/aseptic procedures (N = 19)     0.063
  Hand rubbing/washing 10 (52.6) 5 (26.3)   
  No hand rubbing/washing 0 (0) 4 (21.1)   
 After body fluid exposure risk (N = 18)    6.0 0.125
  Hand rubbing/washing 8 (44.4) 6 (33.3)   
  No hand rubbing/washing 1 (5.6) 3 (16.7)   
 After touching a patient (N = 287)    3.1 < 0.001
  Hand rubbing/washing 140 (48.8) 99 (34.5)   
  No hand rubbing/washing 32 (11.1) 16 (5.6)   
 After touching patient surroundings (N = 56)    1.1 1.000
  Hand rubbing/washing 16 (28.6) 15 (26.8)   
  No hand rubbing/washing 14 (25.0) 11 (19.6)   
Overall (N = 3047)    3.2 < 0.001
  Hand rubbing/washing 1337 (43.9) 1047 (34.4)   
  No hand rubbing/washing 327 (10.7) 336 (11.0)   
  1. aMcNemar’s tests were used to analyse the differences between overtly and covertly observed hand hygiene compliance in each category
  2. bDay shift, 0800–1600 h; early night shift, 1600–2400 h; late night shift, 2400–0800 h